Air precleaners and methods that centrifugally separate heavier-than-air particles from the air to be used in internal combustion engines, ventilation systems, and other apparatus that draw in air laden with debris, are known. These include powered air precleaners which employ a motor-driven fan for drawing debris laden air into the air precleaner as well as air precleaners which rely solely upon a vacuum applied to the precleaner by the device being supplied with clean air, such as an internal combustion engine, for drawing debris laden air into the precleaner. The known air precleaners can include a filter, and/or be used in combination with a device downstream of the clean air outlet of the precleaner having a filter, for removing additional debris from the air. Examples of assignee's prior air precleaners are shown in U.S. Patent numbers                U.S. Pat. No. 5,656,050        U.S. Pat. No. 5,766,315        U.S. Pat. No. 6,319,304        U.S. Pat. No. 6,338,745        U.S. Pat. No. 6,406,506        U.S. Pat. No. 6,425,943        U.S. Pat. No. 6,878,189        U.S. Pat. No. 7,056,368        U.S. Pat. No. 7,452,409.        
Drawbacks of the known air precleaners include that they can be too big for limited space applications and they can require custom manufacturing of an individual air precleaner for a particular application due to variations in configuration and performance requirements. This limits the applications of the air precleaners and adversely effects the time and cost for their manufacture. Examples of air precleaner variations between applications which require individual customization include the required direction of ejection of centrifugally separated particulate debris from the precleaner to atmosphere, the orientation of the clean air outlet for providing clean air from the precleaner to the device with which it is used, the size of a filter in the device, the location of the available supporting structure for mounting the air precleaner, and the clean airflow rate required from the precleaner. In the case of powered air precleaners, the life of the motor of the motor-driven fan in the precleaner has been found to be reduced due to debris/dirt buildup on the motor which lowers the cooling thereof. Further, it has been found that the ejection ports for ejecting debris laden air centrifugally separated from the rotating airflow in the air precleaner are subject to being clogged thereby lowering operational efficiency and decreasing filter life.
There is a need for an improved air precleaner and air cleaning method which overcome these drawbacks and limitations of the known air precleaners. More particularly, there is a need for an improved air precleaner that is compact permitting its use in limited space applications, and is versatile for use in applications with different configurations and clean airflow rate requirements thereby obviating the necessity of a complete custom manufacturing of an individual air precleaner for each application and reducing the time and expense of manufacturing. There is a need for a powered air precleaner which can extend the motor life of a motor driven fan therein. There is also a need for an improved air precleaner and air cleaning method which will facilitate restoring the precleaner to its full operating potential in the event the ejector ports of the precleaner have become clogged.
The improved versatile compact air precleaner, air cleaning method and disposable air filter cartridge of the present invention address these needs. The versatile compact air precleaner of the invention for separating heavier-than-air particulate debris from debris laden air to provide a clean airflow in accordance with a disclosed embodiment comprises a flow path extending through the precleaner from an inlet to an outlet, a motor-driven fan with a fan blade to draw particulate debris laden air into the inlet and flow the debris laden air along the flow path, and an airflow management structure positioned along the flow path to rotate debris laden air drawn into an inlet about an axis to form a rotating flow that stratifies the debris laden air with the heaviest particles in the outermost orbits of the rotating flow. A separator chamber in the flow path centrifugally separates and removes particulate debris laden air from the rotating flow. At least one ejector port is provided through which particulate debris laden air is ejected from the rotating flow in the separator chamber. The flow path for air passing through the separator chamber is retroflexed en route to the outlet. The precleaner of the disclosed embodiment is elongated in the direction of the axis with the inlet and the at least one ejector port located at opposite ends and the outlet located intermediate the ends. By retroflexing the flow path in this manner the air precleaner is more compact permitting use in applications with limited space.
Connection of the air precleaner to a supporting structure/device is facilitated by the provision of at least one mount on the precleaner for mounting the precleaner on the support/device. Versatility is improved for using the device in various configurations in that the air precleaner has means for independently adjusting a radial position of each of the outlet, the at least one ejector port and the at least one mount about the axis of the precleaner to configure the precleaner for mounting on the device and connection to the inlet thereof. In the disclosed embodiment, the means for independently adjusting a radial position includes a housing having a plurality of housing sections arranged sequentially along the axis of the air precleaner and means for releasably connecting and adjustably rotating the sections with respect to one another about the axis. The inlet is located on a housing section apart from that of the at least one ejector port and the outlet and is releasably connected to the precleaner. Accordingly, the inlet configuration can be readily changed permitting adaptation of the air precleaner for ingress of air directly from the atmosphere or indirectly from an air supply conduit connected to the inlet. The adjustability afforded by these features allows the use of a single air precleaner in many different applications/configurations and also facilitates, with only minimal changes, the use of different sizes of filters within the air precleaner and changeover of the air precleaner to meet different airflow rate requirements.
The disclosed, preferred embodiment of the air precleaner of the invention comprises a motor-driven fan with a fan blade mounted on an output shaft of a motor. The fan blade is located in the flow path upstream of the separator chamber and draws particulate debris laden air into the inlet and flows the debris laden air along the flow path. The motor-driven fan is supported on a shroud of the airflow management structure. The shroud tapers outwardly with respect to the axis downstream of the fan blade and shields the motor of the motor-driven fan from the incoming air. A plurality of stationary vanes of the airflow management structure rotate the incoming debris laden air about the axis, compressing the volume of debris laden air to increase the air velocity and centrifugal force acting on the airborne particles. The motor of the motor-driven fan beneath the shroud is in the flow path downstream of the separator chamber, which advantageously reduces dirt and debris buildup on the motor for improved cooling and longer motor life.
The air precleaner of the embodiment further comprises an air filter which forms an inner wall of the separator chamber for filtering air from the innermost orbits of the rotating flow. The flow path for air through the separator chamber is retroflexed en route to the outlet after passing through the filter. The filter is tubular, preferably cylindrical and has a longitudinally extending internal passage for flowing filtered air from the separator chamber toward an outlet of the air precleaner.
The separator chamber includes a separator chamber end section which includes the at least one ejector port. The separator chamber end section is connected to one end of the air filter and is, together with the air filter, removably connected with the air precleaner as a disposable air filter cartridge. Thus, the ejection ports are thrown away with the filter at filter change thereby restoring the air precleaner to its full operating potential if the ports have been clogged during the past filter cycle.
An air cleaning method of the present invention comprises drawing heaver-than-air particulate debris laden air into an inlet of an air precleaner, flowing the particulate debris laden air along the flow path in the precleaner, rotating the flow of the debris laden air about an axis in the precleaner to form a stratified rotating flow with the heaviest particles in the outermost orbits of the rotating flow, ejecting particulate debris laden air from the outermost orbits of the stratified rotating flow through at least one ejector port of the precleaner, filtering air from the innermost orbits of the stratified rotating flow through an air filter extending along said axis within the rotating flow, flowing the filtered air along the flow path toward an outlet of the air precleaner, including utilizing a removable, disposable air filter cartridge in the air precleaner wherein the air filter and the at least one ejector port are integral parts of the removable, disposable air filter cartridge. In accordance with the method, the filtered air leaving the air filter is flowed past the motor of the motor driven fan en route to the outlet of the air precleaner.
A disposable air filter cartridge according to the invention for use in an air precleaner as part of a separator chamber wherein particulate debris laden air is centrifugally separated and removed from a rotating flow of debris laden air through at least one ejector port located within a wall of the separator chamber, comprises a tubular air filter for forming an inner wall of the separator chamber in the air precleaner and filtering air from the innermost orbits of a rotating flow of debris laden air in the separator chamber, the tubular air filter having a longitudinally extending internal passage for flowing filtered air from the separator chamber toward an outlet of the air precleaner, a separator chamber end section securely connected to one end of the tubular air filter and extending radially outwardly from the filter for forming a portion of the wall of the separator chamber, at least one ejector port formed in the separator chamber end section for removal of debris laden air from the rotating flow in the separator chamber, and means permitting releasable connection of the air filter cartridge to the air precleaner.
These and other objects, features and advantages of the present invention will become more apparent from the following description of a preferred embodiment in accordance with the invention when taken in connection with the accompanying drawings.